2002 Tahoe e-fans and volt gauge

[Marky Dissod]

One of the OTHER many things altered in the tune is as follows:
When the electrical fans kick on, they can kick on LOW speed, or HIGH speed. (Older vehicles would be one fan=LOW, or both=HIGH.)
If the AC psi is high enough, both electrical fans can go from off to HIGH in under a second.
That instantaneous current draw could be the cause of your symptoms, especially over 30MpH.

Over 30MpH, HIGH should be completely unnecessary.
My pcm tune does not allow HIGH over 30MpH, so I've never experienced your symptoms.

 

[Fless]

The alternator shown is a 130A unit based on the part number (19244745).

EDIT: you could have some issues with compromised battery cables and grounds, and may want to consider replacing some of them and doing the "big 3." You could also test for voltage drop between the + and - battery connections and the engine block and body.

 

[88lance]

The alternator shown is a 130A unit based on the part number (19244745).

EDIT: you could have some issues with compromised battery cables and grounds, and may want to consider replacing some of them and doing the "big 3." You could also test for voltage drop between the + and - battery connections and the engine block and body.

I don't really know what the big 3 is, can you explain?
So I need to put a volt meter at each end of the cables and see if they are fluctuating also?

 

[justirv]

I don't really know what the big 3 is, can you explain?
So I need to put a volt meter at each end of the cables and see if they are fluctuating also?

The "Big 3" is a grounding upgrade strategy to address grounding issues. Do a search on that, I don't have a link readily available. Highly recommended as the old ground straps were marginally sized, and by now may have significant internal corrosion, impacting conductivity.